1. Field of the Invention
The present invention relates to a sheet feed mechanism for feeding a plurality of stacked sheets one at a time.
2. Description of the Related Art
Facsimile equipments and printers have each a hopper for accommodating a stack of a plurality of sheets, and a sheet feed mechanism for feeding the sheets one at a time from the hopper to feed the sheet for reading characters printed on the sheets or for printing characters on the sheet.
British Patent No. 1,225,883 discloses such a sheet feed mechanism, which comprises a hopper, a feed roller disposed adjacent to the outlet of the hopper so as to be in contact with the lowermost sheet, and a sheet restricting member disposed opposite to the feed roller. In feeding the sheets, the feed roller drives the lowermost sheet while the sheet restricting member restrains the rest of the sheets lying on the lowermost sheet in contact with the feed roller.
The sheet restricting member can be moved substantially perpendicularly to the sheets placed in the hopper. Accordingly, the width of a gap formed between the sheet restricting member and the feed roller at the outlet of the hopper can be varied according to the thickness of the sheets.
This sheet feed mechanism, however, has a problem that, in some cases, a sheet warped sideways driven by the feed roller interferes with the sheet restricting member. The width of the gap between the sheet restricting member and the feed roller must be increased to avoid the interference between the sheet and the sheet restricting member. However, increase in the width of the gap affects adversely the restricting function of the sheet restricting member, excessive increase in the width of the gap entails the feed of a plurality of superposed sheet at a time, which makes the normal printing operation of the printer or the normal character reading operation of the facsimile impossible.